CreateFile API failing with virtual COM port driver create..

Hello there,

We developing virtual COM port driver. (For the purpose : We have a
legacy application that outputs only to COM port and a usb hardware
device). We are using "usbser.sys" as virtual COM port driver. We are
able to install the driver successfully.

But when we use APIs like CreateFile etc with the created COM port.,
the APIs fail with GetLastError reporting 2(system can not find
specified path). Also if i see device manager -> Ports (COM & LPT)
section, the virtual COM driver is listed with an exclaimation mark
with below error,-

"This device can not start (Code 10)"

Also on other test machine it shows error like below,-

"Windows cannot load the device driver for this hardware. The driver
may be corrupted or missing. (Code 39)"

Anybody has inputs on this ? Thanks in advance!

Vijay